The research objective is to elucidate the molecular basis of the process by which lung phagocytes ingest objects, the principal mechanism by which these cells defend hosts against pulmonary infection. The motor aspect of the phenomenon is being studied by attempting a complete characterization of contractile proteins from lung macrophages. We are studying: actin-binding protein, a structural protein that crosslinks actin filaments into a gel; gelsolin, a calcium-activated protein that severs actin filaments; myosin and a myosin cofactor, required for activation of actomyosin contractile activity, and a protein that keeps actin in an oligomeric state.